Fallow Season Research Articles

Evaluation N2O Emissions from Intensive Manure Managements in a Dairy Area

To investigate N2O emissions from intensive manure managements, eight farmer’s fields covering paddy rice and uplands cropping systems in a livestock watershed of central Japan has been selected. The manure was popular applied with PIAF (Ploughing Immediately after Fertilization), FKSSL (Fertilizer Keeping on the Surface Soil for a Longer Time) and only applied in winter fallow season for paddy rice under the application rate of 200-800 kg N ha-1yr-1. Field gas samples were conducted by static chamber method. The result showed that N2O flux varied from 0 to 1607 μg N m-2h-1 in upland crop systems and from 0 to 924 μg N m-2 h-1 in paddy fields. And the annual emission ranged from 1.91- 9.26 kg N ha-1 yr-1 accounting for 0.48 ± 0.41% of input N in uplands and 1.28-1.91 kg N ha-1 yr-1 accounting for 0.43 ± 0.27% of input N in paddy rice, respectively. In rice/fallow system, more N2O emitted and the emission factor was 0.59 ± 0.07% due to the manure applied in fallow winter season. The N2O emission from FKSSL was 0.85 ± 0.79% of input N, and 3.4 times higher than PIAF. Slurry application contributed N2O emission 0.71 ± 0.37% of input N with 2 times higher than that of dry compost manure plots.

Comparison of fallow season CO<SUB>2</SUB> efflux from paddy soil estimated using laboratory incubation with eddy covariance-based flux

Comparison of fallow season CO<SUB>2</SUB> efflux from paddy soil estimated using laboratory incubation with eddy covariance-based flux

Macrobenthic Community Structure During Fallow Season in Kole Paddy Fields, Northern Kerala, India

Despite the recognized contribution of benthic fauna in nutrient enhancement, very little information is available from Indian paddy fields. This study analyzed the benthic community structure during fallow season in Kole paddy fields, a part of Vembanad Kole wetlands (a Ramsar site), Northern Kerala, India. Study area during fallow season was characterized by isolated water patches amidst of terrestrial vegetation (grass). The macrobenthic fauna belonged to the phyla Annelida, Arthropoda, Mollusca and families Tubificidae, Naididae, Chironomidae, Ceratopogonida, Chaoboridae, Ceratopogonidae, Gyrinidae and Bithynidae. These organisms possessed various survival mechanisms that ensured their survival against dry periods. Insects were the major benthic organisms; the habitat fragmentation due to isolated distant water patches during fallow season favored insect taxa more due to their active/flight mode of dispersal compared to oligochaetes which are benthic crawlers. Macrobenthic abundance was less (166±60 ind./m2), attributed to reduced habitable area for benthos due to habitat desiccation. A decline in abundance was apparent from January to June 2010, the beginning to end of fallow season except in April where the onset of rain after a dry spell made the dry area wet, thereby making the inactive dormant forms of organisms live, resulting in an increased abundance. Diversity analysis of benthic families revealed that highest richness (d) of 1.235 was in March and diversity (H') of 2.603 was in March. No significant correlation emerged between benthic abundance and the measured environmental parameters, implying that the interaction of biota and physico chemical variables was overridden by someother unmeasured factors.

Macrobenthic Community Structure During Fallow Season in Kole Paddy Fields, Northern Kerala, India

Despite the recognized contribution of benthic fauna in nutrient enhancement, very little information isavailable from Indian paddy fields. This study analyzed the benthic community structure during fallow seasonin Kole paddy fields, a part of Vembanad Kole wetlands (a Ramsar site), Northern Kerala, India. Study area during fallow season was characterized by isolated water patches amidst of terrestrial vegetation (grass). Themacrobenthic fauna belonged to the phyla Annelida, Arthropoda, Mollusca and families Tubificidae, Naididae,Chironomidae, Ceratopogonida, Chaoboridae, Ceratopogonidae, Gyrinidae and Bithynidae. These organismspossessed various survival mechanisms that ensured their survival against dry periods. Insects were the majorbenthic organisms; the habitat fragmentation due to isolated distant water patches during fallow season favoredinsect taxa more due to their active/flight mode of dispersal compared to oligochaetes which are benthiccrawlers. Macrobenthic abundance was less (166±60 ind./m2), attributed to reduced habitable area for benthosdue to habitat desiccation. A decline in abundance was apparent from January to June 2010, the beginning toend of fallow season except in April where the onset of rain after a dry spell made the dry area wet, therebymaking the inactive dormant forms of organisms live, resulting in an increased abundance. Diversity analysis of benthic families revealed that highest richness (d) of 1.235 was in March and diversity (H') of 2.603 was inMarch. No significant correlation emerged between benthic abundance and the measured environmentalparameters, implying that the interaction of biota and physico chemical variables was overridden by some other unmeasured factors

Response of soil water, temperature, and maize (Zea may L.) production to different plastic film mulching patterns in semi-arid areas of northwest China

Plastic film mulching has been used widely to increase crop productivity in dryland farming. In this study, to identify the optimal mulching pattern and ensure the efficient utilization of soil water in the semi-arid areas of northwest China, we tested the following five treatments for 3 years (2013–2015): (1) full amount of plastic film with flat mulching (FL mulching) throughout the whole season (FLW), or (2) only during the growing season (FLG); (3) alternating ridges and furrows where only the ridges were mulched with plastic film (RF mulching) throughout the whole season (RFW), or (4) only during the growing season (RFG); (5) flat planting without mulching throughout the whole season (NM). The results showed that FLW was more beneficial for reducing soil water losses during the fallow season compared with RFW. FL mulching enhanced soil water consumption during the maize growing season, but promoted maize production compared with RF mulching due to the increased soil temperature. The rainfall was low during July–September in 2015, and the soil water storage at harvest under FLW and FLG were 9.13mm higher and 8.01mm lower than the stable soil water, respectively, thereby suggesting that FLW increased the soil water supply capacity in this drought year, and thus it was more sustainable in terms of soil water utilization compared with FLG. With FLW, the average yield increased by 838kgha−1, 1944kgha−1, 2363kgha−1, and 5164kgha−1, compared with FLG, RFW, RFG, and NM, respectively, and the average net income increased by 244USDha−1, 520USDha−1, 643USDha−1, and 1166USDha−1. These results suggest that FLW was an effective method for substantially increasing economic benefits and maize yields in semi-arid areas.

Effects of bamboo biochar application on global warming in paddy fields in Ehime prefecture, Southern Japan

ABSTRACTBiochar application can reduce global warming via carbon (C) sequestration in soils. However, there are few studies investigating its effects on greenhouse gases in rice (Oryza sativa L.) paddy fields throughout the year. In this study, a year-round field experiment was performed in rice paddy fields to investigate the effects of biochar application on methane (CH4) and nitrous oxide (N2O) emissions and C budget. The study was conducted on three rice paddy fields in Ehime prefecture, Japan, for 2 years. Control (Co) and biochar (B) treatments, in which 2-cm size bamboo biochar (2 Mg ha−1) was applied, were set up in the first year. CH4 and N2O emissions and heterotrophic respiration (Rh) were measured using a closed-chamber method. In the fallow season, the mean N2O emission during the experimental period was significantly lower in B (67 g N ha−1) than Co (147 g N ha−1). However, the mean CH4 emission was slightly higher in B (2.3 kg C ha−1) than Co (1.2 kg C ha−1) in fallow season. The water-filled pore space increased more during the fallow season in B than Co. In B, soil was reduced more than in Co due to increasing soil moisture, which decreased N2O and increased CH4 emissions in the fallow season. In the rice-growing season, the mean N2O emission tended to be lower in B (−104 g N ha−1) than Co (−13 g N ha−1), while mean CH4 emission was similar between B (183 kg C ha−1) and Co (173 kg C ha−1). Due to the C release from applied biochar and soil organic C in the first year, Rh in B was higher than that in Co. The net greenhouse gas emission for 2 years considering biochar C, plant residue C, CH4 and N2O emissions, and Rh was lower in B (5.53 Mg CO2eq ha−1) than Co (11.1 Mg CO2eq ha−1). Biochar application worked for C accumulation, increasing plant residue C input, and mitigating N2O emission by improving soil environmental conditions. This suggests that bamboo biochar application in paddy fields could aid in mitigating global warming.

Drainage and tillage practices in the winter fallow season mitigate CH<sub>4</sub> and N<sub>2</sub>O emissions from a double-rice field in China

Abstract. Traditional land management (no tillage, no drainage, NTND) during the winter fallow season results in substantial CH4 and N2O emissions from double-rice fields in China. A field experiment was conducted to investigate the effects of drainage and tillage during the winter fallow season on CH4 and N2O emissions and to develop mitigation options. The experiment had four treatments: NTND, NTD (drainage but no tillage), TND (tillage but no drainage), and TD (both drainage and tillage). The study was conducted from 2010 to 2014 in a Chinese double-rice field. During winter, total precipitation and mean daily temperature significantly affected CH4 emission. Compared to NTND, drainage and tillage decreased annual CH4 emissions in early- and late-rice seasons by 54 and 33 kg CH4 ha−1 yr−1, respectively. Drainage and tillage increased N2O emissions in the winter fallow season but reduced it in early- and late-rice seasons, resulting in no annual change in N2O emission. Global warming potentials of CH4 and N2O emissions were decreased by 1.49 and 0.92 t CO2 eq. ha−1 yr−1, respectively, and were reduced more by combining drainage with tillage, providing a mitigation potential of 1.96 t CO2 eq. ha−1 yr−1. A low total C content and high C / N ratio in rice residues showed that tillage in the winter fallow season reduced CH4 and N2O emissions in both early- and late-rice seasons. Drainage and tillage significantly decreased the abundance of methanogens in paddy soil, and this may explain the decrease of CH4 emissions. Greenhouse gas intensity was significantly decreased by drainage and tillage separately, and the reduction was greater by combining drainage with tillage, resulting in a reduction of 0.17 t CO2 eq. t−1. The results indicate that drainage combined with tillage during the winter fallow season is an effective strategy for mitigating greenhouse gas releases from double-rice fields.

Greenhouse gas emissions as affected by different water management practices in temperate rice paddies

The mitigation of methane (CH4) and nitrous oxide (N2O) emissions from rice paddy fields is pivotal in minimizing the impact of rice production on global warming. The large majority of the world rice is cropped in continuously flooded paddies, where soil anaerobic conditions lead to the production and emission of significant amounts of CH4. In this work we evaluated the effectiveness of water management techniques alternative to the conventional flooding on the mitigation of CH4 emissions from paddy soils, and verified whether any concurrent increase in N2O emissions can totally or partially offset their environmental benefit. Two alternative water management systems were compared to the conventional continuous flooding system (WFL): dry seeding with delayed flooding (DFL) and intermittent irrigation (DIR). Methane and N2O emissions were monitored at field-scale over two years including both rice cropping and fallow seasons, using non-steady-state closed chamber approach. The DFL system resulted in a 59% decrease (average of the two measured years) in total CH4 emissions with respect to WFL, while DIR annulled CH4 emissions. The effect of CH4 mitigation of DFL with respect to WFL was mainly concentrated within the vegetative stage, while any significant flux from DIR was recorded throughout the growing and non-growing season. However, DIR resulted in the highest emission peaks and cumulative fluxes of N2O, almost totally occurred during the vegetative stage. In contrast, DFL and WFL showed N2O emissions that were 77 and 93% lower with respect to DIR, respectively. Total annual fluxes suggest that the adoption of alternative water management practices that involve dry seeding and subsequent delayed flooding or intermittent irrigation can contribute to significantly reduce the global warming potential of rice cropping systems by 56 and 83%, respectively with respect to continuous flooding.

Predicting intra-seasonal fluctuations of NDVI phenology from daily rainfall in the East Sahel: a simple linear reservoir model

ABSTRACTShort-term predictive models are essential for understanding the temporal relationships between the variability of impulsive daily rainfall and the attendant dynamics of vegetation development in rangelands, particularly for the water-limited, semi-arid East Sahel. After identifying selected rain-dependent sites in southeast Sudan, this report applies a procedure to predict seasonal biomass development in response to impulse-like daily storm events using a simple linear reservoir model as an analogue for the coupled soil–plant–atmosphere ecosystem. Key parameters are the characteristic time () of the reservoir and the number (n) of elementary reservoirs in series. Surface vegetative biomass is represented by the normalized difference vegetation index (NDVI) provided by the MODIS satellite MOD13A2 16 day 1 × 1 km product. Our specific metric is the commonly used differential NDVI, or δNDVI, the difference between the actual NDVI value and its long-term fallow season baseline. We review the concept of the modelling method, with selected application to 15 years (2000−2014) of NDVI data from a 51 × 51 km study area in the East Sahel, centred on the standard WMO Gauge 62752 at Gedaref City in southeast Sudan. Results indicate that as few as four – even as few as two – model parameters might be used to describe intra-seasonal to multiple-year vegetation dynamics. Allowing for inter-annually variable parameters, the predicted results exhibit a coefficient of determination of 0.96. An alternative formulation using a single set of four, seasonally dependent model parameters, globally determined from 15 years of observed reference data, results in a coefficient of determination of 0.90; a version using only two, globally determined model parameters works almost as well for the type of phenology characteristic of this area. In addition to enabling a number of applications that would benefit from the availability of a synthetic phenological time series that is solely dependent on daily rainfall, one of the most important applications may be for infilling data gaps in the observed time series, which for this area of the Sahel are typically encountered during early-season green-up; a critical time for most NDVI studies. We found that the 1 year lagged autocorrelation coefficient, and some version of the conventional rain use efficiency (RUE) factor with its associated annual correlation coefficient, are essential adjunct screening parameters when identifying sites with the highest inter-annual variability in biomass production (typical of the most natural rain-fed sites in this area).

Soil nitrate–N residue, loss and accumulation affected by soil surface management and precipitation in a winter wheat-summer fallow system on dryland

Soil nitrate–N residue after harvesting crops and nitrate–N loss during the following fallow season is serious concern for the agricultural environment in dryland. A 6-year-long, location-fixed field experiment was conducted to determine the effects of plastic film mulch (PM), straw mulch (SM), green manure (GM) and straw mulch plus green manure (SGM) on the nitrate–N residue, loss and accumulation in a winter wheat-summer fallow system. Compared with the bare fallow, average grain yield was increased by 6 % with PM, whereas decreased by 7, 5 and 5 % with SM, GM and SGM, respectively. Average total N uptake was decreased by 13 % with SM, but not affected by PM, GM and SGM. Average nitrate–N residue at wheat harvest was decreased by 35, 32 and 18 % with PM, SM and SGM, respectively, but not affected by GM. Average soil water recharge was increased by 12 % with PM, and not affected by SM, whereas decreased by 20 and 16 % with GM and SGM, respectively. For the PM, SM, GM and SGM, the average nitrate–N loss from top soil was decreased by 51, 53, 50 and 34 %, respectively, and the average nitrate–N accumulation in deep soil was decreased by 56, 45, 31 and 39 %. Above results revealed that increasing the yield decreased soil nitrate–N residue, and nitrate–N loss and accumulation was restricted by the decreased nitrate–N residue and soil water recharge. Overall, PM is a preferable measure for the decreased nitrate–N residue, loss and accumulation, at the same time increased the yield in dryland.

Alternate wetting and drying in high yielding direct-seeded rice systems accomplishes multiple environmental and agronomic objectives

Rice (Oryza sativa L.) cultivation is critically important for global food security, yet it also represents a significant fraction of agricultural greenhouse gas (GHG) emissions and water resource use. Alternate wetting and drying (AWD) of rice fields has been shown to reduce both methane (CH4) emissions and water use, but its effect on grain yield is variable. In this three-year study we measured CH4 and nitrous oxide (N2O) emissions, rice grain total arsenic (As) concentrations, yield response to N rate, and grain yield from two AWD treatments (drill-seeded and water-seeded) and a conventionally managed water-seeded treatment (control). Grain yields (average=10Mgha−1) were similar or higher in the AWD treatments compared to the control and required similar or lower N rates to achieve these yields. Furthermore, AWD reduced growing season CH4 emissions by 60–87% while maintaining low annual N2O emissions (average=0.38kgN2O–Nha−1);N2O emissions accounted for <15% of the annual global warming potential (GWP) in all treatments. Fallow season emissions did not vary by treatment and accounted for 22–53% of annual CH4 emissions and approximately one third of annual GWP on average. The AWD treatments reduced annual GWP by 57–74% and growing season yield-scaled GWP by 59–88%. Milled grain total As, which averaged 0.114mgkg−1 in the control, was reduced by 59–65% in the AWD treatments. These results show that AWD has the potential to mitigate GHG emissions associated with rice cultivation and reduce rice grain total As concentrations without sacrificing grain yield or requiring higher N inputs; however future research needs to focus on adapting AWD to field scales if adoption of this technology is to be realized.

Breaking the Cycle of Xanthomonas campestris pv. musacearum in Infected Fields through the Cultivation of Annual Crops and Disease Control in Adjacent Fields

Cultivation of non-host crops after uprooting Xanthomonas campestris pv. musacearum (Xcm)-infected banana plants has been advocated for breaking Xanthomonas wilt disease (XW) cycle in fields. Knowledge on the interaction of these crops with Xcm is limited. Maize, beans and sweet potato were planted after uprooting Xcm-infected banana plants in Rwanda and eastern Democratic Republic of Congo (DR Congo). A weed fallow (mixed species) served as the control. After one, two and/or four break-crop or fallow seasons, healthy plantlets were replanted and monitored for XW for 12–24 months. XW status in adjacent fields was monitored, and diseased stems within 100–300 m radius of the two- and four-season experiments were uprooted. In Rwanda, soil and plant parts from the one-season experiments were sampled for Xcm isolation and Xcm-like colonies confirmed with Xcm-specific primers using PCR. Pathogenicity tests were performed to confirm the ability of the PCR-positive isolates to infect healthy banana plantlets. XW was observed in all the one-season experiments, with higher cumulative incidences in maize and bean plots. However, no similar trends were observed in the two-season experiments, with a 6–8% incidence observed only in bean and potato plots in DR Congo. Lengthening time under break crops to two and four seasons, respectively, reduced the incidence to 3% and zero in Rwanda and 0–8% in the two-season experiments in DR Congo. Incidence in the first-season experiments highly correlated (R = 88) to that in the adjacent fields, suggesting possible re-infections from these fields. Two season with break crop plus collective XW control are recommended in these agro-ecosystems. PCR-positive Xcm-like colonies from break crops only induced localized cell death on banana, while PCR-positive isolates from symptomatic banana plants caused full XW symptoms. Cross-infection/inoculation studies under controlled conditions are still needed to conclusively elucidate Xcm interaction with these crops.

Effects of slow/controlled release urea on annual CH4 and N2O emissions in paddy field.

Present study examined the influence of different types of slow/controlled release urea on rice yield and annual greenhouse gas emissions in a paddy field, and assessed the greenhouse gas intensity (GHGI, equivalent to global warming potential GWP/rice yield). The results indicated that the optimized fertilization (OPT) treatment recorded the similar yield with reduced nitrogen fertilizer (21.4%) supply compared with the farmers' fertilizer practice (FFP) treatment, and decreased the annual emissions of CH4 (12.6%) and N2O (12.5%) during the rice season, and N2O emission (33.3%) during the fallow period. Application of controlled release urea (CRU) reduced CH4 emission by 28.9% during the rice-growing season with respect to OPT treatment, and showed negligible CH4 emission during the fallow season. However, nitrification inhibitor (DMPP) treatment was found to reduce the CH4 emissions by 41.6% and 76.9%, and N2O emissions by 85.7% and 6.5%, during the rice growing season and fallow season, respectively, compared with OPT treatment. In the fallow season, the N2O emissions accounted for 76.8%-94.9% of annual N2O emissions, which was clearly a key point for evaluation of greenhouse gas emissions in paddy. The average values of GHGI in OPT, CRU and DMPP treatments were 0.50, 0.41 and 0.33 kg·kg-1, respectively. Considering the benefits of higher rice yield and lower annual greenhouse gas emissions, combined application of urea and nitrification inhibitor could be the best combination in paddy fields.

Winter cover crops alter methanotrophs community structure in a double-rice paddy soil

Methanotrophs play a vital role in the mitigation of methane emission from soils. However, the influences of cover crops incorporation on paddy soil methanotrophic community structure have not been fully understood. In this study, the impacts of two winter cover crops (Chinese milk vetch (Astragalus sinicus L.) and ryegrass (Lolium multiflorum Lam.), representing leguminous and non-leguminous cover crops, respectively) on community structure and abundance of methanotrophs were evaluated by using PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) and real-time PCR technology in a double-rice cropping system from South China. Four treatments were established in a completely randomized block design: 1) double-rice cropping without nitrogen fertilizer application, CK; 2) double-rice cropping with chemical nitrogen fertilizer application (200 kg ha–1 urea for entire double-rice season), CF; 3) Chinese milk vetch cropping followed by double-rice cultivation with Chinese milk vetch incorporation, MV; 4) ryegrass cropping followed by double-rice cultivation with ryegrass incorporation, RG. Results showed that cultivating Chinese milk vetch and ryegrass in fallow season decreased soil bulk density and increased rice yield in different extents by comparison with CK. Additionally, methanotrophic bacterial abundance and community structure changed significantly with rice growth. Methanotrophic bacterial pmoA gene copies in four treatments were higher during late-rice season (3.18×107 to 10.28×107 copies g–1 dry soil) by comparison with early-rice season (2.1×107 to 9.62×107 copies g–1 dry soil). Type I methanotrophs absolutely predominated during early-rice season. However, the advantage of type I methanotrophs kept narrowing during entire double-rice season and both types I and II methanotrophs dominated at later stage of late-rice.

A soil carbon proxy to predict CH4 and N2O emissions from rewetted agricultural peatlands

The temporal and spatial variations in greenhouse gas (GHG) emission estimates in wetlands impede our ability to predict and upscale total emissions; thus, a scalar parameter is needed to predict GHG emissions. We investigated the importance of soil organic carbon (SOC) in the prediction of methane (CH4) and nitrous oxide (N2O) emissions in rewetted agricultural peatlands, positing that both CH4 and N2O production are explained by the quantity and turnover of SOC. Field CH4 and N2O fluxes, along with other edaphic and environmental variables, were monitored in rewetted peatlands with a range of SOC (6%, 11%, and 23%) that were recently converted from row crops to flooded rice cultivation to reverse soil subsidence. Nitrogen (N) fertilization reduced annual CH4 emission by 77.2% in the 6% C field, but this effect was not found in other fields. Annual N2O emissions were not affected by N fertilization and averaged 8.9, 5.2, and 1.9kgN2O-Nha−1 for the 6%, 11%, and 23% C fields, respectively. SOC was the dominant factor controlling both CH4 and N2O emissions. The annual emission for both CH4 and N2O was accurately described by a decaying power regression with increasing SOC contents (R2>0.49). This relationship was also observed after splitting total annual emission of CH4 and N2O into growing and fallow seasons. Nitrogen fertilization and the seasonality in CH4 and N2O emissions did not change the relationships. The inverse correlation between SOC and CH4 and N2O emissions was likely caused by different chemical composition of SOC in various soils. Our results suggest that SOC can be a potential proxy to predict CH4 and N2O emissions in rewetted peatlands to better define GHG predictions of wetland restoration efforts.

Greenhouse gases emission from paddy soil during the fallow season with and without winter flooding in central Japan

Many papers on measurements of greenhouse gases (GHGs) emission in rice paddies during a rice cropping season have been published. During a non-cropping season between Nov. and Apr., we investigated direct and indirect GHGs emissions in rice paddies. The indirect GHGs emission was evaluated as the amount of dissolved gases leaching from the paddy fields. Water management practices for the experiment were (1) continuous flooding (CF) and (2) non-flooding (NF). Although the direct CO2 emission in the CF treatment was remained nearly zero during the non-cropping period, direct CO2 emission in the NF treatment was continuously observed throughout the non-cropping period. The concentration of dissolved N2O in the NF treatment was below the detection limit of the instrument during the non-cropping period except immediately after the flooding and before the drainage. The concentration of dissolved N2O kept approximately 2 µg L−1 during the non-cropping period in the CF treatment. The direct CH4 emission and dissolved CH4 were not observed during the non-cropping period. Total gas emission in the NF treatment was 10 times as large as that in the CF treatment. Direct CO2 emission accounted for more than 90 % of the total emission in both treatments.

冬季水分管理和水稻覆膜栽培对川中丘陵地区冬水田CH_4排放的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 冬季水分管理和水稻覆膜栽培对川中丘陵地区冬水田CH4排放的影响 DOI: 10.5846/stxb201405301111 作者: 作者单位: 土壤与农业可持续发展国家重点实验室 中国科学院南京土壤研究所,四川省农业科学院土壤肥料研究所,土壤与农业可持续发展国家重点实验室 中国科学院南京土壤研究所,中国科学院南京土壤研究所,四川省农业科学院土壤肥料研究所,四川省农业科学院土壤肥料研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(41271259);科技部国际科技合作项目(2012DFG90290);公益性行业(农业)科研专项(201103039);中国香港特别行政区嘉道理农场暨植物园资助 Effects of water management in winter and of plastic film mulching during rice cultivation on CH4 emission from paddy field in a hilly region of Central Sichuan Author: Affiliation: State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Science,Institute of Soil Fertilizer,Sichuan Agriculture Sciences Academy,State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Science,State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Science,Institute of Soil Fertilizer,Sichuan Agriculture Sciences Academy,Institute of Soil Fertilizer,Sichuan Agriculture Sciences Academy Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:采用静态箱-气相色谱法观测冬季水分管理和水稻覆膜栽培对川中丘陵地区冬水田全年的CH4排放通量。试验设置持续淹水(CF)、冬季直接落干+稻季淹水(TF)与冬季覆膜落干+稻季覆膜(PM)3个处理。结果表明,冬季休闲期,CF、TF和PM处理CH4排放分别为16.1、1.4 g/m2和2.7 g/m2;水稻生长期,CF、TF和PM处理CH4排放分别为57.7、27.7 g/m2和13.5 g/m2。相较于CF处理,TF与PM处理分别减少其全年CH4排放60.6%和78.0%。TF与PM处理水稻生长期CH4排放峰值分别较CF处理低33.0%和56.1%。休闲期,TF、PM处理厢面与厢沟区域CH4排放与土壤温度显著正相关(P < 0.05),与土壤氧化还原电位(土壤Eh)显著负相关(P < 0.05),而CF处理CH4排放仅与土壤温度显著正相关(P < 0.05)。水稻生长期,CF处理CH4排放与土壤温度显著正相关(P < 0.05),与土壤Eh显著负相关(P < 0.05),TF处理CH4排放仅与土壤Eh显著负相关(P < 0.05),PM处理厢沟CH4排放与土壤Eh显著正相关(P < 0.05)。各处理水稻生长期土壤可溶性有机碳含量(DOC)与微生物生物量碳含量(MBC)显著高于休闲期(P < 0.05)。研究结果为进一步研究冬水田全年CH4排放规律及寻求有效的减排措施提供数据支撑和科学依据。 Abstract:Methane (CH4) is one of the most important greenhouse gases and plays an important role in atmospheric chemistry. Rice fields have been identified as an important source of atmospheric CH4. Because permanently flooded paddy fields create the most favorable situation for CH4 production and emit CH4 all year round, they are thought to contribute the greatest amounts of CH4. Draining the permanently flooded paddy fields in the fallow season is supposed to be a good option for mitigating CH4 emission. However, those paddy fields distributed in the hilly area of southwest China face the problem of water shortage. This means that transplanting rice in the following year would be hindered, if the fields were drained in the previous fallow season. In recent years, a new technology involving improved plastic film mulching for rice cultivation has been developed. It is an alternative to permanently flooded rice cultivation technology, which promises to save water, and in addition, would allow drainage in the fallow season without impeding the next rice transplanting session. The effects of water management in winter and of plastic film mulching during rice cultivation on CH4 emission throughout the year were explored using winter paddy fields in the hilly region of Central Sichuan. A field experiment was carried out using the static chamber-gas chromatograph method to monitor CH4 emissions in the paddy fields. Three treatments were designed: Treatment CF (continuous flooding all year round), Treatment TF (drained in winter and flooded during the rice growing season), and Treatment PM (drained and mulched in winter and mulched during the rice growing season). The results showed that methane emission for Treatments CF, TF, and PM was 16.1 g/m2, 1.4 g/m2, and 2.7 g/m2, respectively, during the winter fallow season and 57.7 g/m2, 27.7 g/m2, and 13.5 g/m2, respectively, during the rice-growing season. Compared with Treatment CF, Treatments TF and PM reduced the annual CH4 emission by 60.6% and 78.0%, respectively, and lowered the CH4 flux peak during the rice-growing season by 33.0% and 56.1%, respectively. During the fallow season, in Treatments TF and PM, CH4 emission from ridge and ditch areas was significantly correlated with soil temperature (P < 0.05), but negatively with soil redox potential (soil Eh) (P < 0.05). However, CH4 emission was positively correlated with soil temperature in Treatment CF (P < 0.05). During the rice-growing season, in Treatment CF, CH4 emission was significantly and positively related to soil temperature (P < 0.05), and negatively to soil Eh (P < 0.05). In Treatment TF, CH4 emission was only negatively related to soil Eh (P < 0.05), and in Treatment PM, CH4 emission from the ditches was significantly and positively related to soil Eh (P < 0.05). The soil dissolved organic carbon (DOC) and soil microbial biomass carbon (MBC) contents were much higher during the rice-growing season than during the fallow season (P < 0.05). The findings may provide important data and a scientific basis for further study of the process of CH4 emission from permanently flooded paddy fields throughout a year and to explore effective mitigation options for CH4 emission in more detail. 参考文献 相似文献 引证文献

Global warming as affected by incorporation of variably aged biomass of hairy vetch for rice cultivation

Hairy vetch (Vicia villosa Roth) is cultivated during the cold fallow season in paddy soils of temperate countries such as South Korea and Japan, mostly as animal feed and green manure. Information on the effect of ageing of hairy vetch incorporation in relation to greenhouse gas (GHG) emissions and global warming potential (GWP) is not available. Therefore, hairy vetch biomass of ages 183, 190, 197, and 204 days was incorporated in paddy soil to estimate GWP during rice cultivation. The emission rates of methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) gases were monitored once a week by using the closed-chamber method. The net ecosystem carbon budget was used to estimate pure CO2 emission fluxes. Biomass production of hairy vetch was 6.5 Mg ha–1 at 204 days, which was similar to other treatments. The GWP was lower with the 204-day-old vetch biomass incorporation than with other treatments. High content of cellulose and lignin in 204-day-old hairy vetch might have affected decomposition rate and subsequently reduced GHGs emissions during rice cultivation. Our results suggest that hairy vetch can be allowed to grow for 204 days before incorporation at 3 Mg ha–1 without sacrificing rice yield, while maximising biomass production and minimising GWP during rice cultivation.

Methane and Nitrous Oxide Emissions Reduced Following Conversion of Rice Paddies to Inland Crab-Fish Aquaculture in Southeast China.

Aquaculture is an important source of atmospheric methane (CH4) and nitrous oxide (N2O), while few direct flux measurements are available for their regional and global source strength estimates. A parallel field experiment was performed to measure annual CH4 and N2O fluxes from rice paddies and rice paddy-converted inland crab-fish aquaculture wetlands in southeast China. Besides N2O fluxes dependent on water/sediment mineral N and CH4 fluxes related to water chemical oxygen demand, both CH4 and N2O fluxes from aquaculture were related to water/sediment temperature, sediment dissolved organic carbon, and water dissolved oxygen concentration. Annual CH4 and N2O fluxes from inland aquaculture averaged 0.37 mg m(-2) h(-1) and 48.1 μg m(-2) h(-1), yielding 32.57 kg ha(-1) and 2.69 kg N2O-N ha(-1), respectively. The conversion of rice paddies to aquaculture significantly reduced CH4 and N2O emissions by 48% and 56%, respectively. The emission factor for N2O was estimated to be 0.66% of total N input in the feed or 1.64 g N2O-N kg(-1) aquaculture production in aquaculture. The conversion of rice paddies to inland aquaculture would benefit for reconciling greenhouse gas mitigation and agricultural income increase as far as global warming potentials and net ecosystem economic profits are of concomitant concern. Some agricultural practices such as better aeration and feeding, and fallow season dredging would help to lower CH4 and N2O emissions from inland aquaculture. More field measurements from inland aquaculture are highly needed to gain an insight into national and global accounting of CH4 and N2O emissions.

Assessing carbon dynamics at high and low rainfall agricultural sites in the inland Pacific Northwest US using the eddy covariance method

Agricultural soils have the potential to be an important carbon (C) sink with proper management. The main goal of this study was to characterize C dynamics and net C exchange over two full crop years at two sites in the inland Pacific Northwest (iPNW). The iPNW is a highly productive dryland wheat growing region. The two measurement sites represent the low- and high-end of the regional precipitation gradient (250 and 550mmyear−1, respectively). The low rainfall site is in a winter wheat-fallow rotation, while the high rainfall site is under continuous cropping with a rotation that includes winter wheat and pulse crops. The net ecosystem exchange of CO2 (NEE) was monitored using the eddy covariance method. The winter wheat cropping years were strong CO2 sinks, with net uptake of 517±26 and 524±29gCm−2year−1 at the high- and low-rainfall sites, respectively. The fallow and pulse-crop years were close to neutral with respect to NEE, with a net uptake of 20±38gCm−2year−1 for garbanzo beans at the high rainfall site, and a net loss of 3±19gCm−2year−1 for the fallow season at the low rainfall site. Combining NEE with other carbon exchange terms, most importantly carbon import and export via seeding and harvest, gives the net ecosystem carbon balance (NECB). We found that even when harvest export was taken into account, both sites acted as net carbon sinks over the two year period: the NECB at the continuous cropping site was 202±60gCm−2, and the crop-fallow site had a NECB of 444±34gCm−2. These results present useful insights to field-scale C dynamics on finely resolved timescales. To understand the potential of soils as a long term C sink however, longer-term monitoring over multiple complete crop rotation cycles in combination with other field measurements or process-based models will be necessary.